/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *     http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.apache.giraph.bsp;

 import org.apache.hadoop.io.Writable;

 import org.apache.hadoop.io.WritableComparable;

 import java.io.IOException;

 /**

  * Basic service interface shared by both {@link CentralizedServiceMaster} and

  * {@link CentralizedServiceWorker}.

  *

  * @param <I> Vertex id

  * @param <V> Vertex value

  * @param <E> Edge value

  * @param <M> Message data

  */

 @SuppressWarnings("rawtypes")

 public interface CentralizedService<I extends WritableComparable,

     V extends Writable, E extends Writable, M extends Writable> {

   /**

    * Setup (must be called prior to any other function)

    */

   void setup();

   /**

    * Get the current global superstep of the application to work on.

    *

    * @return global superstep (begins at INPUT_SUPERSTEP)

    */

   long getSuperstep();

   /**

    * Get the restarted superstep

    *

    * @return -1 if not manually restarted, otherwise the superstep id

    */

   long getRestartedSuperstep();

   /**

    * Given a superstep, should it be checkpointed based on the

    * checkpoint frequency?

    *

    * @param superstep superstep to check against frequency

    * @return true if checkpoint frequency met or superstep is 1.

    */

   boolean checkpointFrequencyMet(long superstep);

   /**

    * Clean up the service (no calls may be issued after this)

    *

    * @throws IOException

    * @throws InterruptedException

    */

   void cleanup() throws IOException, InterruptedException;

 }